This invention relates to a transmission system for a marine drive.
In a conventional marine drive, including an engine and a propulsion unit, the engine is directly and mechanically connected to the propeller through a gear box. As a result, the speed of the propeller is directly proportional to the speed of the engine in a ratio established by the gears of the gear box.
It has been recognized that the usual selection of marine drive characteristics provides unsatisfactory boat performance at low-speed operation, such for trolling or docking. Mechanisms for improving the low-speed performance of a boat are disclosed in my copending patent applications Ser. No. 07/255,618 filed Oct. 11, 1988, now U.S. Pat. No. 4,887,984, Ser. No. 07/118,862 filed Nov. 9, 1987, now U.S. Pat. No. 4,820,209 and Ser. No. 07/232,703, filed Aug. 16, 1988, now U.S. Pat. No. 4,919,009 Ser. No. 07/255,618 now U.S. Pat. No. 4,887,984, discloses a fluid coupling apparatus in connection with a series of stationary variable position vanes disposed between the pump and the turbine components of the fluid coupling. The vanes are movable so as to govern the direction of impingement of fluid on the turbine component of the fluid coupling. The position of the vanes governs the amount of power transferred from the fluid pump to the turbine, as well as the direction of rotation of the turbine. Ser. No. 07/118,862, now U.S. Pat. No. 4,820,209, discloses a fluid coupling structure including a fluid pump, a forward driven turbine and a reverse, or reaction, driven turbine. The forward and reaction turbines are connected to concentrically extending shafts. Through a series of gears, clutches and brakes, the forward and reverse turbine shafts drive an output shaft in either a first or second rotational direction, for propelling the boat in either a forward or reverse direction. A variable force brake is operable on the output shaft, to control, its, power output. Ser. No. 07/232,703 now U.S. Pat. No. 4,919,009, discloses a fluid coupling transmission having forward and reverse turbines which are rotatable in the same direction of rotation in response to rotation of a fluid pump. A one-way clutch is provided on the forward turbine for transmitting power to an output shaft only in one direction of rotation. A planetary gearset is provided between the reverse turbine and the output shaft, and the planet gears of the gearset are rotatably mounted to a carrier member. A selective engagement mechanism, including a plate clutch disposed between the carrier member and the output shaft, and a brake band selectively engageable with the carrier member, is operable to control the direction of rotation of the output shaft. The reverse turbine includes a series of movable vanes for providing variable power output from the transmission.
The present invention is also directed to a structure for providing improved low-speed and variable speed operation of a boat. A fluid coupling is provided between the marine drive engine and the gear box to which the propeller is connected. The fluid coupling includes a rotatable fluid pump connected to the engine and rotatable in response to rotation of the engine crankshaft. A rotatable turbine is adapted to be driven by the fluid pump, and a series of variable position vanes are provided between the fluid pump and the turbine at the entrance of fluid into the fluid pump, for controlling power transfer therebetween by governing the amount of fluid entering the pump, and thereby exiting the pump and acting on the turbine. A rotatable output shaft is provided for outputting power from the fluid coupling, and a sun gear is fixed to the output shaft. A ring gear is connected to and rotatable with the turbine, and one or more planet gears are disposed between the sun gear and the ring gear. An output control means governs the direction of rotation of the rotatable output shaft. In one embodiment, the one or more planet gears are rotatably mounted to a carrier member, which extends concentrically along at least a portion of the length of the output shaft. The output control means includes a clutch mechanism for selectively clutching the carrier member to the output shaft, and a brake mechanism for selectively preventing rotation of the carrier member. A lock-up clutch is provided for directly mechanically coupling the output shaft to the fluid pump, so as to bypass the effect of the fluid coupling in response to certain predetermined operating conditions.
With the above-described construction, the brake mechanism and the clutch mechanism can be selectively engaged to prevent rotation of the output shaft, or to provide rotation of the output shaft in either a first or a second direction of rotation.